Skip-stitch mechanism for household sewing machines



Se t. 9, 1969 w. HACK LANDER 3,465,693

SKIP-STITCH MECHANISM FOR HOUSEHOLD SEWING MACHINES Filed Oct. 6', 1967 2 Sheets-Sheet 1 I NVEVTOR. Hons W. Hocklonder BY W ATTO WITNESS:

P 9, 969 H. w. HACKLANDER 3,465,698

SKIP-STITCH MECHANISM FOR-HOUSEHOLD SEWING MACHINES Filed Oct. 6, 1967 2 Sheets-Sheet 2 I NVENTOR.

Hans W. Hacklonder BY wnmzss; ML4Z 34w M ATTO NEY United States Patent 3,465,698 SKIP-STITCH MECHANISM FOR HOUSEHOLD SEWING MACHINES Hans W. Hacklander, Huntsville, Ark., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Oct. 6, 1967, Ser. No. 673,429 Int. Cl. DOSh 3/02, 69/02 US. Cl. 112-158 9 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION In some of the prior art sewing mechanisms capable of skip-stitching the normal thread concatenation is prevented by utilizing various methods such as manipulation of the looper or needle thread or by providing special needles or attachments in the bed of the sewing machine. In these prior art skip-stitch devices the needle penetrates the work material during the skipping of the stitches which results in undesirable needle holes in all work material and prohibits use with some work fabrics in which such holes cannot be tolerated. In addition, the mechanisms utilized are either not sufficiently reliable for modern, sophisticated household sewing machines, occupy too much space or are inconvenient in that needles or attachments have to be changed each time skip-stitches are required.

In other prior art sewing mechanisms capable of skipstitching the reciprocation of a needle-bar is interrupted to prevent formation of stitches. In one such type of mechanism, one of two needle-bars mounted in the machine is manually disconnected to aid the operator in the production of square corners. The United States Patent No. 2,346,467, Apr. 11, 1944, Bills et al., discloses another needle-bar interrupting mechanism, which, however, is built into an industrial type tufting machine that does not have zigzag stitching capability. The combination of needle jogging motion with correlated needlebar interruption does not exist in the Bills et al. tufting machine. The Bills et al. needle-bar interrupting mechanim serves only for controlling the location of tuft formation and is continuously under the control of a permanently mounted cam, which mechanism cannot, therefore, readily be called into or out of action. Since the Bills et al. tufting machine is constructed so that reciprocation of the needle-bar is continuously under the control of the permanently mounted cam it can be utilized for only one type of stitching operation. Furthermore, the Bills et al. tufting machine utilizes a twosection main shaft to effect skip-stitching which is more expensive to manufacture and more difficult to install than a unitary main shaft. In addition, the Bills et al. skipstitch mechanism is bulky and occupies a large amount of space relative to the size of the machine.

SUMMARY OF THE INVENTION The present invention comprises needle-bar interrupting mechanism mounted within the confines of the frame of a sewing machine and responsive to needle-bar interrupting program means. The needle-bar is driven in ice endwise reciprocation by actuating mechanism including a unitary shaft mounted for rotation in the sewing machine frame. The interrupting mechanism includes mechanism, responsive to said program means, that serves to move a driving member mounted on and rotatable with the unitary shaft, The driving member is moved endwise along the unitary shaft into our out of operative engagement with a driven member that is operatively connected to the needle-bar. The driven member drives the needle-bar in endwise reciprocation when the driving and driven members are operatively engaged. The needle-bar interrupting mechanism serves to interrupt the endwise reciprocation of the needle-bar at predetermined intervals dependent upon the construction of the program means. The present invention also provides mechanism effective during operation of the actuating mechanism for rendering the needle-bar interrupting mechanism non-responsive to the program means.

The disclosed embodiment of the present invention avoids the drawbacks of the prior art skip-stitching mechanisms briefly outlined above by placing its relatively small and compact skip-stitch mechanism in an unused area of the sewing machine and by utilizing some of the existing zigzag mechanism. The skip-stitch mechanism of the present invention is reliable and does not require an exchange of needles or attachments when skipstitches are desired, and of course since the skip-stitches are produced by interrupting the reciprocation of the needle-bar no undesirable perforations are made in the work material during the skip-stitch mode of operation. Furthermore, the present invention utilizes a unitary main shaft which is less expensive to manufacture than a twopiece shaft and is easier to mount within the bracket arm than the two-piece shaft.

It is an object of the present invention to provide an improved skip-stitch mechanism for a zigzag sewing machine.

It is another object of the present invention to provide an improved mechanism for interrupting the vertical re ciprocation of the sewing machine at predetermined intervals.

It is still another object of this invention to provide improvements in skip-stitch mechanism that utilize a cam actuated sleeve mounted for endwise movements on the sewing machine arm shaft.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when made in conjunction With the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of the sewing machine in which the present invention is embodied with the top cover plate removed.

FIG. 2 is a sectional view taken substantially along line 22 of FIG. 1,

FIG. 3 is an exploded perspective view of the skipstitch mechanism of the present invention,

FIG. 4 is a sectional view taken substantially along line 44 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawings, there is illustrated a zigzag sewing machine having a frame including a substantially vertical standard 10 which carries a horizontal bracket arm 12 that terminates in a head 14. The open upper end of the bracket arm 12 is closed by a conventional top cover plate (not shown). Journaled longitudinally of the arm is a one-piece or integrally formed main shaft 16 that is driven by a belt 18, entrained on a belt pulley 19, from a conventional moto. (not shown). In addition to its other functions, described below, the main shaft 16 drives loop taker mechanism (not shown) which cooperates with a needle carried by a needle-bar 20 to provide normal thread concatenation.

The needle-bar 20 is mounted for endwise reciprocation in a needle-bar gate 22 which gate is pivotally mounted in the head 14 and is spring biased in a counterclockwise direction, as viewed from above. Endwise reciprocation is imparted to the needle-bar 20 by a crank 24 mounted in the head 14 and connected by a link 26 pivoted to the needle-bar.

The zigzag mechanism of this machine will now be described in such detail as to be sufficient for an understanding of this disclosure. However, in the event that a more complete understanding is desired reference may be made to the United States Patent No. 3,074,364, issued on Aug. 28, 1962, to Ralph E. Johnson. Lateral vibrations are imparted to the needle-bar 20 by a zigzag mechanism including a vertically disposed tubular cam shaft 28 having a central bore for receiving and thereby journaling the cam shaft upon a stud 30 mounted on a vertical axis in a boss 32 integral with the front wall of the bracket arm 12. The lower portion of the cam shaft 28 has formed thereon a gear 34 that meshes with a worm 36 secured to the main shaft 16 for imparting rotation to the cam shaft 28 upon rotation of the main shaft 16. A stitch pattern cam 38 is formed with a peripheral cam surface 40 and is mounted on the upper end of the cam shaft 28. A clamping nut 42 is rotatably mounted on a reduced upper section of the stud 30 and is threaded into the upper end of a bore in the cam shaft 28 releasably to clamp the cam 38 onto the cam shaft 28.

The zigzag actuating mechanism of the disclosed machine includes a vertically arranged stud 44 secured to the rear of the bracket arm 12. Pivotally mounted on the stud 44 is a bracket 46 in which is mounted a pivot pin 48. Pivotally mounted on the pin 48 is a U-shaped plate 50 formed of sheet metal and arranged generally transversely of the bracket arm 12, and cut away as at 52 to accommodate the main shaft 16 and the worm 36. The plate 50 is formed at its upper section with an ear 54 formed with an aperture that slidably receives the pin 48 at its upper section, and the plate 50 is also formed at its lower end with an car (not shown) having an aperture that slidably receives the pin 48 at its lower end. A cam follower 56 formed of sheet metal is pivotally mounted on a pivot screw 58 in turn mounted on an ear bent from the top of the plate 50. On the forward end of the cam follower 56 there is integrally formed an upstanding follower element 60 that is adapted to cooperate with the peripheral cam surface 40 of the pattern cam 38. The rearward end of the follower 56 is bifurcated to provide a slot 62 that receives a reduced diameter section 64 of the stud 44 to support the rear end of the cam follower against movement endwise of the stud 44 and to provide a sliding pivot for the same.

The U-shaped plate 50 is formed with a lower arm 66 in which is formed a slot 68 through which extends one end of a pitman 70 that extends through the bracket arm 12 toward the head 14. At its other end the pitman 70 is connected by a bolt 72 to a bracket 74. The bracket 74 is pivotally connected to the needle-bar gate 22 by a pin 76 which extends loosely through an arm of the bracket and is secured to an upper bearing lug of the needle-bar gate. The connection between the end of the pitman 70 and the plate 50 includes a block 78 secured by a screw 80 on the end of the pitman and disposed on that side of the plate 50 opposite from the needle-bar gate 22.

The bracket 46 determines the center adjustment of the ornamental stitch pattern by varying the position of the 4 pivot pin 48 which defines the pivot axis for the plate 50. Adjustment of the bracket 46 is provided by a handle 82 secured to a locking plate 84 by a screw 86.

The pitman 70 is biased to the left, as viewed in FIGS. 1 and 2, and thereby biases the U-shaped plate 50 in a clockwise direction, as viewed in FIG. 1, about the axis of the pivot pin 48. The plate 50, through the pivot screw 58, biases the cam follower 56 about its pivot axis, which is defined by the vertically arranged stud 44, to engage the follower element 60 against the peripheral pattern surface 40 of the pattern cam 38. Upon rotation of the pattern cam 38 oscillation is imparted to the cam follower 56. Through the pivot screw 58 oscillation of the cam followers 56 oscillates the plate 50 about the axis of the pivot pin 48. Through engagement of the plate 50 and the block 78 as the plate 50 is oscillated the pitman 70 is pulled to the right, FIGS. 1 and 2, in opposition to the bias exerted on the needle-bar gate and is released for movement to the left in response to the bias exerted on the needle-bar gate. Endwise movement of the pitman imparts lateral vibration to the needle-bar gate 22. The amplitude of the endwise movement imparted to the pitman 70 and thus the lateral vibration of the needle-bar may be varied by adjusting handle 88 which acts to vary the setting of the block 78 radially relatively to the pivot axis of the plate 50 by means which will not be described in this specification since it is unnecessary for an understanding of the invention disclosed herein.

Turning now to a description of the skip-stitch mechanism of the present invention, the crank 24 is secured by a set screw 90 on an elongated sleeve 92 which slidingly receives the main shaft 16 and is in turn received by a bearing 94 that is secured to the head 14 by a set screw 96. The shaft 16 is journaled at its other end section in a bearing 97 secured in the bracket arm 12 at the standard end thereof. Thus, the main shaft 16 may rotate within the sleeve 92 and the crank 24 is driven only when the sleeve 92 is rotated. The main shaft 16 is prevented from sliding endwise out of the sleeve 92 by a spacer washer 98 and a snap ring 100 mounted on the head end of the shaft.

The elongated sleeve 92 is countersunk in the end section closest the standard to form a circular opening 102 adapted to receive a coil spring 104 which is wrapped about the main shaft 16 and abuts against a seat 106, formed on the inner wall of the sleeve by the opening, and against a washer 108 mounted on the main shaft 16 between the coil spring and an end face 110 of a spool shaped sleeve (which may be formed of plastic or other suitable material) 112. The elongated sleeve 92 has formed on its outer surface intermediate its end a step 114 that presents a face 116 between which an end face 118 of bearing 94 there is fitted a washer 120. The sleeve 92 is also formed, at its standard end, with a shoulder 122 having a spiral face 124 on the side of the shoulder closest the head and a substantially flat face 126 on the opposite side thereof. The spiral face 124 has formed therein a substantially rectangularly shaped recess 128 and the fiat face 126 has formed thereon a lug 130 extending outwardly toward the sleeve 112 parallel with the main shaft 16.

A sleeve positioning device is indicated generally by the numeral 132 (FIG. 3) and includes an elongated block 134 having a depending section bifurcated to form a pair of ears 136 that form a slot 138 between them. The block 134 is mounted on two threaded lugs 140 that are secured by nuts 142 in threaded holes in bosses 144 formed on either side of the sewing machine frame, the free ends of the lugs being received by matching holes 146 formed in either side of the block 134. The slot 138, formed between the ears 136, is adapted to receive a substantially T-shaped plastic member 148 formed with a depending stop lug 150, the member 148 being secured between the ears 136 by a pair of screws 152. The block 134 is biased in a counterclockwise (FIG. 2) direction by a tension spring 154 that is connected at one end to a boss 156 in the sewing machine frame and at the other end to the block 134. The block 134 also supports an adjustment screw 158, formed with a contact end 160, which is threaded through an aperture in the ears 136 and which may be locked in place by a nut 162. The bias exerted by the spring 154 serves constantly to keep the contact end 160 of the screw 154 in engagement with the face 110 of the spool shaped sleeve 112.

The spool shaped sleeve 112 is formed with a central aperture 164 that receives the main shaft 16 and is also formed with a slot 166 that is rectangular in cross section, extends the length of the spool and opens into the central aperture 164. The slot 166 is adapted to receive an elongated stub 168, rectangular in cross section, that is secured to and extends radially of the main shaft 16. The stud 168 extends lengthwise of the shaft 16 a distance roughly equal to the length of the spool shaped sleeve 112. Thus, the spool shaped sleeve 112 may be moved endwise along the main shaft 16 but is prevented from turning relatively to the shaft by locking engagement of the stud 1-68 with the slot 166. The end face 110 of the spool shaped sleeve 112 has integrally formed thereon a driving lug 170 that extends towards the sleeve 92 parallel to the main shaft 16.

The coil spring 104 normally biases the spool shaped sleeve 112 to the right (FIGS. 1 and 2) against the lower arm of a cam follower unit 172 formed with a vertically arranged sleeve-like body section 174 pivotally mounted on a bolt 176 that threadedly engages a boss 178 in the frame of the machine. Integrally formed with the body section 174 and extending radially from the body section is a lower arm 188 and an upper cam follower arm 182 in substantial vertical alignment with each other. The upper arm 182 includes a finger 184 that may be brought into operative engagement with a peripheral cam surface 186 of a readily exchangable skip-stitch cam 188 mounted beneath the cam 38 on the cam shaft 28. The lower arm 180 includes a finger 190 against which end face 192 of sleeve 112 is biased.

To selectively bring the skip-stitch mechanism into operation there is provided a lever arm 194 formed at one end section with an elongated slot 196 and having the other end section offset vertically as at 198, the offset section being formed near its open end with an aperture 200. The elongated slot 196 slidably receives a vertically arranged bolt 202 which in turn threadedly engages an opening 204 formed in the cam follower arm 182. The lever arm 194 is pivotally connected to a connecting arm 206 by a bolt 208 which is received by the aperture 200 in the end of the lever arm. The connecting arm 206 is pivotally connected by its other end on a bolt 210 which is secured in a boss 212 of the machine frame and a control handle 214 is secured by one end section to an intermediate section of the arm 206. Extending from and integral with the front end of the arm 206 is a finger 216 that is connected to a bobbin winding unit 218 that includes a wheel 220 which is fixedly mounted on a bobbin receiving spindle 222. The control handle 214 is constructed of spring steel and acts to bias the handle upwardly to seat the same in one of three notches A, B or C formed in the front wall of the bracket arm 12. It is noted that all of the skip-stitch mechanism is mounted within the confines of the sewing machine frame beneath the top cover plate, thereby permitting the machine to retain its streamlined shape. In addition the skip-stitch mechanism is mounted in areas of the machine that are normally not utilized. This effects a saving in space which is important in modern home sewing machines because of the increasing use of ancillary mechanisms, as for instance buttonholing devices and the like, mounted therein. Furthermore by utilizing part of the existing zigzag mechanism, i.e., the cam shaft and drive therefor, a further saving in space is effected in addition to the reduction in cost made possible by having the skip-stitch mechanism and the zigzag mechanism share the cam shaft.

In operation the cam shaft 28 iscontinuously driven by the unitary main shaft 16 through the worm 36 and gear 34 thereby rotating the cams 38 and 188 at a speed determined by the rotation of the shaft 16. As set forth above the needle-bar is given its lateral or zigzag movement by the mechanical train that extends from the cam follower 56, which responds to the cam 38, through the needlebar gate 22.

With the central handle 214 in the position shown in FIG. 1, i.e. with the handle set in the notch B, the finger 184 of the cam follower arm 182 is biased into cam tracking engagement with the peripheral cam surface 186 of the skip-stitch cam 188 by the coil spring 104. As the cam 188 rotates, in cooperation with the coil spring 104, it pivots the cam follower unit 172 in a clockwise or counterclockwise direction (FIG. 1) depending upon the section of the cam that is, at the time, engaged by the finger 184. When the cam follower unit 172 is pivoted in a counterclockwise direction (FIG. 1) the finger 190 of the lower arm 188 is moved to the left (FIG. 1) to engage and move the spool shaped sleeve 112 to the left along the main shaft 16 against the bias of the coil spring 104. As the sleeve 112 moves to the left (FIGS. 1 and 2) the adjustment screw 158 is also moved to the left thereby to pivot the sleeve positioning device in a clockwise direction and remove the stop lug 150 from the recess 128 which frees the sleeve 92 for rotation on the main shaft 16. Simultaneously, the rotating driving lug 170 is moved into the path of the lug of the elongated sleeve 92 so that the rotating sleeve 112 will entrain the sleeve 92, which is now free to rotate, thereby to rotate the sleeve 92 which in turn rotates the crank 24 and imparts endwise reciprocation to the needle-bar 20. It is noted that the sleeve 112 is moved to the left far enough to engage the flat face 126 of the sleeve 92, thereby eliminating wearing of the lug 170 through contact between the lug 17 0 and the face 126. When, thereafter, the cam follower unit 172 is pivoted clockwise, the driving lug 170 moves out of the path of the lug 130 on the sleeve 92 thereby to terminate the driving relationship between the sleeve 112 and the sleeve 92. Simultaneously the stop lug of the sleeve positioning device 132 is pulled into engagement with the spiral face 124 of the sleeve 92 by the action of the spring 154. The spiral shape of the face 124 permits the lug 150 gradually to approach the recess 128 thereby to provide a smooth engagement of the lug with the recess. Were it not for the spiral shape of the face 124, i.e. if the face 124 were fiat, at the high speeds that the main shaft is rotated the lug 150 would very often skip over the recess 128 thereby permitting the needle-bar to reciprocate more than the number of times desired, which would alter the predetermined (by the cam 188) skip-stitch pattern.

By moving the handle 214 into the notch C the operator may, after disengaging the pulley from the main shaft to prevent needle reciprocation, wind bobbins on the spindle 222 in the conventional manner.

When the operator moves the handle 214 toward the notch A the lever arm 194 moves to the left (FIGS. 1 and 2) thereby to bring the right end (FIG. 1) of the elongated slot 196 into engagement with the bolt 202 which is secured to the cam followed arm 182. Further movement of the handle into the notch A serves to move the bolt 202 to the left and pivot the cam follower unit 172 counterclockwise (FIG. 1) so that the sleeves 92 and 112 are brought into operative engagement and the finger 184 of the cam follower arm 182 is removed from track ing engagement with the periphery of the skip-stitch cam 188. Since, in the A position the sleeves remain in operative engagement the operator may sew continuously in the conventional non-skip-stitch mode.

Having thus set forth the nature of this invention, what is claimed herein is:

1. A sewing machine having a frame, including a hollow bracket arm terminating at its free end in a head, a needle carrying bar mounted in said head, actuating means carried on said frame, a first arm shaft bearing mounted in the head extremity of the bracket arm and a second arm shaft bearing mounted in the standard extremity of the bracket arm, means operatively connected to said actuating means for imparting movement including endwise reciprocatory movement to said needle-bar, said actuating means including an integrally formed rotary arm shaft journaled longitudinally of said bracket arm in said arm shaft bearings, carn means mounted on said sewing machine for programming the interruption of the reciprocation of said needle-bar at intervals determined by the configuration of the cam means, means for operatively connecting said actuating means to said needle-bar reciprocation interrupting program means, means for interrupting the endwise reciprocatory movement of said needle-bar at predetermined intervals in response to operation of said program means, said interrupting means including a driving member mounted on said integrally formed arm shaft, means for permitting endwise movement of said driving member relatively to said integrally formed arm shaft and for locking said driving member for rotary movement with said integrally formed arm shaft, a driven member mounted for rotary movement within said frame, means for operatively connecting said driven member to said needle-bar, means for providing for a driving engagement between said driving member and said driven member when said integrally formed arm shaft is rotated thereby to drive said needlebar in endwise reciprocation, means for holding said needlebar in a raised position upon interruption of the endwise reciprocation of said needle-bar, and manually operable control handle means effective during operation of said actuating means for selectively rendering said needle-bar reciprocation interrupting means non-responsive to said program means.

2. A sewing machine as set forth in claim 1 wherein said driven member comprises a sleeve received by said first arm shaft bearing, said integrally formed arm shaft being journaled in said sleeve, said means for operatively connecting said driven member to said needle-bar including a needle-bar crank secured to said sleeve.

3. A sewing machine having a frame including a hollow bracket arm terminating at its free end in a head, a needlebar carried in said head for endwise reciprocatory and lateral jogging movements, actuating means carried on the frame, a first arm shaft bearing mounted in the head extremity of the bracket arm and a second arm shaft bearing mounted in the standard extremity of the bracket arm, means driven by said actuating means for imparting endwise reciprocatory movements to said needle-bar, said actuating means including an integrally formed rotary arm shaft journaled longitudinally of said bracket arm in said arm shaft bearings, a cam shaft mounted in said bracket arm, means operated by said actuating means for driving said cam shaft, cam means carried by said cam shaft, means for removably mounting said cam means on said cam shaft, means responsive to said cam means for imparting lateral jogging movements to said needle-bar to provide for the production of zigzag stitches, means mounted within the confines of said bracket arm for interrupting the endwise reciprocation of said needle-bar at predetermined intervals, means responsive to said cam means for effecting operation of said needle-bar interrupting means, said means for interrupting the endwise reciprocation of said needle-bar including a driving member mounted on said integrally formed rotary arm shaft, means for permitting endwise movement of said driving member relatively to said integrally formed rotary arm shaft and for locking said driving member for rotary movement with said integrally formed rotary arm shaft, a driven member mounted for rotary movement within said frame, means for operatively connecting said driven member to said needle-bar, means for providing for a driving engagement. between said driving member and said driven member to drive said driven member when said integrally formed rotary arm shaft is rotated thereby to drive said needle-bar in endwise reciprocation, means for holding said needle-bar in a raised position upon interruption of the endwise reciprocation of said needle-bar, and means effective during operation of said actuating means for selectively rendering said needle-bar interrupting means non-responsive to said cam means.

4. A sewing machine as set forth in claim 3 wherein said cam means includes a skip-stitch cam formed with a contoured surface and said means for effecting operation of said needle-bar interrupting means includes a cam follower arm adapted to respond to the contoured surface and a driving member actuating arm operatively connected to said cam follower arm and said driving member.

5. A sewing machine as set forth in claim 3 wherein said driving and driven members are sleeve shaped and said driven member is received by said first arm shaft bearing, said driven member being mounted on said integrally formed rotary arm shaft so that said driven member is rotatable relatively thereto, and including means for biasing said driving sleeve endwise on said integrally formed rotary arm shaft away from driving engagement with said driven sleeve.

6. A sewing machine as set forth in claim 5 wherein said means for operatively connecting said driven sleeve to said needle-bar includes a needle-bar crank fixedly mounted on said driven sleeve for rotation therewith and means for connecting said needle-bar crank to said needle-bar.

7. A sewing machine as set forth in claim 3 wherein said driven member is a sleeve which receives said integrally formed rotary arm shaft about which it is free to rotate and said means for operatively connecting said driven sleeve to said needle-bar includes a needle-bar crank fixedly secured to said driven sleeve for rotation therewith and means for operatively connecting said needle-bar crank to said needle-bar.

8. A sewing machine as set forth in claim 7 wherein said means for holding said needle-bar in a raised position upon interruption of the endwise reciprocation of said needle-bar includes a member pivotally mounted on said frame, a stop lug supported by said member, a radial shoulder formed on the outer surface of said driven sleeve near one end thereof, said radial shoulder being formed with a face extending radially of the outer surface of said driven sleeve, said face being formed with a recess and a spiral surface that terminates in said recess and means for biasing said stop lug into contact with the spiral surface of said face.

9. A sewing machine as set forth in claim 8 wherein said driving member is a sleeve and said driving sleeve and said driven sleeve are formed with opposing end faces, said means for providing for a driving engagement between said driving sleeve and said driven sleeve including a lug extending outwardly from the end face of said driven sleeve and a driving lug extending outwardly from the end face of said driving sleeve in the path of said driven sleeve lug when said sleeves are in driving engagement.

References Cited UNITED STATES PATENTS 2,314,339 3/1943 Bradwell 112221 X 2,333,689 11/1943 Sigoda 11 2221 X 2,346,467 4/1944 Bills et a1 112221 X RICHARD J. SCANLAN, JR., Primary Examiner US. Cl. X.R. 112221 

